Borates, including zinc borate, sometimes associated with aluminum hydrates, have been used in fire resistant coatings and materials for many years. Bisodium borate (Na2B4O7.10H2O) (often called borax) has also been used as a fire retardant and as a preservative for various types of materials including wood, plastic and the like. Bisodium borate is extremely hygroscopic and in its hygroscopic form is vulnerable to solubilization and leaching from the substrate. This is true when it is used as a fire retardant or preservative, thereby reducing effectiveness. Many attempts have been made over the years to stabilize bisodium borate so that it resists leaching from the substrate but such attempts have not been entirely successful.
A number of patents have issued over the years disclosing borates as a fire retardant or preservative.
U.S. Pat. No. 3,897,387, O'Shaughnessy, granted Jul. 29, 1997, and reissued Jan. 15, 1980 as RE30,193, discloses a fire retardant agent comprising calcium or magnesium mineral borates or calcium or magnesium meta borate and a halogen source; a method of rendering organic materials generally of a hydrocarbon nature, such as plastic and rubber polymers, cellulosics, resins and oils, etc., fire retardant by introducing into said organic materials calcium or magnesium mineral borates or calcium or magnesium meta borate and a halide; articles, laminates, coatings, foams, papers, fabrics, etc. containing calcium or magnesium mineral borates or calcium or magnesium meta borate and a halide of atomic weight greater than 19.
U.S. Pat. No. 3,861,425, Clark, granted Jan. 21, 1975, and its continuation-in-part, U.S. Pat. No. 3,945,962, Clark, granted Mar. 23, 1976, disclose a water base, hardenable coating composition for use on the inner or air conducting surfaces of fibrous glass thermal insulation employed in heating, cooling or ventilating conduits. The coating comprises, by weight: 70 to 90 percent of aluminum or magnesium hydrate; 5 to 20 percent of a binder such as vinyl acrylic latex or polyethylene vinyl acetate latex; and 1 to 10 percent of a flame retardant such as a sodium borate or boric acid.
U.S. Pat. No. 3,816,307, Woods, granted Jun. 11, 1974, discloses a composition for rendering resin compositions fire retardant consisting essentially of a dry mixture of particles of a finely divided Group I metal borate or ammonium borate, said borate having an average particle size of from 0.1 to about 25 microns, and antimony oxide, the weight ratio of said borate to antimony oxide being no greater than 4:1.
Often, the borates are combined with other compounds or substances. The following patents disclose borates in combination with other substances.
DE 4,309,142, Bayer AG, published Sep. 29, 1994, relates to flameproofed moulding compositions comprising aromatic polycarbonates, ABS graft polymers, copolymers and a flame-protection combination comprising red phosphorus, phosphate or phosphonate esters, antimony trioxide or boron phosphate, and tetrafluoroethylene polymer, characterised in that the red phosphorus and the phosphorus compounds are added as a batch in pastille (briquette) form, to the use of the moulding compositions for the production of mouldings, and to a process for incorporating the mixture of phosphorus and phosphorus compounds into the moulding composition.
EP 906,934, Ausimont S.p.A., published Apr. 7, 1999, discloses thermoplastic fluoropolymer compositions, flexible, without whitening, comprising: (1) ETFE or ECTFE fluoropolymers modified with hydrogenated monomers; (2) one or more hydrogenated plasticizers; (3) one or more inorganic fire retardants; (4) optionally other ingredients such as fillers, smoke retarders, intumescent agents, pigments, lubricants, organic fire retardants and thermal stabilizers.
U.S. Pat. No. 5,266,618, Watanabe et al., granted Nov. 30, 1993, discloses a flame-retardant resin composition comprising the following components (A), (B), (C) and (D): (A) 100 parts by weight of a thermoplastic resin comprising (1) a polycarbonate resin, or (2) a polycarbonate resin and a non-polycarbonate resin; (B) from 0.1 to 40 parts by weight of a phosphorus compound; (C) from 0.001 to 40 parts by weight of a boron compound; and (D) from 0.01 to 5 parts by weight of a polyorganosiloxane and/or from 0.001 to 5 parts by weight of a fluorine resin.
EP 0,364,729, General Electric, published Apr. 25, 1990, discloses that the flame retardant properties of polymers with an aromatic main chain can be improved by incorporating therein a fluorine compound in combination with a boron compound.
EP 0,921,159, General Electric, published Jun. 9, 1999, discloses flame retardant compositions comprising a polymer of carbon monoxide, and at least one olefin, and a flame retarding quantity of a melamine compound.
JP 11,181,266 Kanegafuchi Chemical Industry, Co., Ltd., Jul. 6, 1999, discloses fire-resistant thermoplastic resin compositions containing boron compounds comprising: (a) 100 parts of a resin blend consisting of 50-100 wt. % of a polycarbonate resin and 0-50 wt. % of a polyester resin; (b) 1-50 parts of a boron compound selected from boron oxide, zinc borate, and zinc borate hydrate; (c) 0.1-50 parts of talc; and (d) 0.005-1 part of a fluoro resin. The ratio of the boron compound and talc is 99:1 to 30:70. The fluoro resin can be a fluorinated polyolefin with average particle size <700 .mu.m.
JP 10,030,056, Mitsubishi Eng. Plastics KK, Feb. 3, 1998, discloses a novel polycarbonate resin composition (I) comprising: (1) 100 parts wt. polycarbonate resin and 5-50 wt. % (B) glass fibre; (2) 1-10 parts wt. (C) phosphoric acid ester(s); (3) 0.1-5 parts wt. (D) boron compound(s); and (4) 0.01-2 parts wt. (E) fibril polytetrafluoroethylene.
JP 5,098,144, Denki Kagaku Kogyo KK, Apr. 20, 1993, discloses a composition comprising (A) a polycarbonate type thermoplastic resin; and (B) a flame retardant agent comprising (a) an organic phosphor compound, (b) an inorganic boron compound and (c) a halogen containing compound. Preferably, the composition comprises a polyorganosiloxane and/or fluorine containing resin. The composition comprises a thermoplastic resin besides the polycarbonate resin.
U.S. Pat. No. 5,314,530, Wierer et al., granted May 24, 1994, discloses coating compositions for producing watertight, vapor-permeable and flame-retardant coatings, comprising a vinyl chloride copolymer or vinyl acetate/ethylene dispersion, flameproofing agents, foam stabilizer and optionally crosslinkers. The invention further relates to a process for producing watertight, vapor-permeable and flame-retardant coatings by mechanically foaming the coating composition to produce a stable foam, applying the foam to a woven, knitted or non-woven support material on one or both of the sides and drying it at a temperature of from 60° to 80° C. and optionally, after drying, compressing the foam layer. The textile support materials coated with the coating composition are suitable for use in building protection and in the geotextile sector.
U.S. Pat. No. 3,945,962, De Paul, granted Mar. 23, 1976, discloses a water base, hardenable coating composition for use on the inner or air conducting surfaces of fibrous glass thermal insulation employed in heating, cooling or ventilating conduits. The coating comprises, by weight: 70% to 90% of aluminum or magnesium hydrate; 5 to 20% of a binder such as vinyl acrylic latex or polyethylene vinyl acetate latex; and 1 to 10% of a flame retardant such as a sodium borate or boric acid.
Chinese Patent No. 1,076,947, People's Republic of China, Oct. 6, 1993, discloses compositions comprising vinyl acetal modified acrylic or acrylate emulsions 23-28, organic nitrides as the curing crosslinker selected from melamine, glycine, guanidine, dicyanamide or urea 13-17, carbon sources selected from pentaerythritol, starch or dextrin 10-14, blowing agents selected from (NH4)3PO4, ammonium phosphate, HN4H2PO4, naborate or (NH4)2SO4 18-22, fillers selected from barium metaborate, mica powder, talc, Kaolin, ZnO, titanium white or Al(OH)3 2-5, flame retardants selected from Mg-rich montmorillonite, quartz powder, borax or zirconium oxide 8-12 wt. % and balance water. The materials are of heat-insulation and can be used as decorative coating.
U.S. Pat. No. 4,539,045, Wagner, granted Sep. 3, 1985, discloses non-blooming fire retardant compositions comprising an ammonium phosphate-containing fire retardant and an effective amount of boric acid or an alkali metal borate. The ammonium phosphate-containing fire retardant preferably comprises the reaction mixture of aqueous phosphoric acid and an alkylene oxide. Preferably, the boric acid or alkali metal borate is present in an amount of from about 2.5% to about 12% by weight of solids in the phosphate-containing fire retardant. Such compositions are less susceptible to exudation of the fire retardant from treated wood panels during drying of the panels at elevated temperatures, and are particularly suitable for use in continuous treatment processes.
U.S. Pat. No. 5,151,127, Thompson, discloses several compositions that purport to combine the properties of being both an effective wood preservative and a fire retardant, while simultaneously being resistant to weather and leaching. These compositions are water-based and contain borax. Further, these compositions are applied to wood and cellulose products by spraying, brushing, rolling, pouring dipping, immersing or pressure impregnation, depending upon the material being treated and the purpose for which it is intended. The compositions disclosed in U.S. Patent No. 5,151,127 consist of various mixtures and proportions of the components listed in the table in column 2, lines 1-15. The specific recipes for compositions I-IX are listed in tabular form starting at column 3, line 49. The compositions disclosed do not contemplate the use of a liquid polytetrafluoroethylene suspension (i.e. durapel), nor specific steps of a method to prepare the fire retardant suspension.
U.S. Pat. No. 5,430,081, Ohmae et al., granted Jul. 4, 1995, discloses a flame retardant thermoplastic resin composition which comprises (A) 50 to 90% by weight of a thermoplastic resin which is the base polymer and 50 to 10% by weight of a total of (B) a nitrogen-containing condensed phosphoric acid compound, (C) a comb-like polymer consisting of a polyethylene main chain and a polyoxyalkylene side chain and (D) a metal-containing compound having a carbonization accelerating effect, the amounts of the components (B), (C) and (D) being 5 to 49% by weight, 1 to 15% by weight and 0 to 10% by weight, respectively, in which the total amount of the components (B), (C) and (D) is 100% by weight; a process for producing the composition; a flame-retardant consisting of the components (B), (C) and (D); and a process for producing the flame-retardant.